JP5207568B1 - Current source inverter device and control method of current source inverter device - Google Patents

Abstract

In controlling a switching element of a current source inverter, switching loss of the switching element is prevented by a normal switching operation for commutation operation without requiring special control.
In the commutation operation of the current source inverter device, the drive timing of the switching element is controlled so that an overlapping section is generated in which both the commutation source switching element and the commutation destination switching element are turned on. The resonance circuit is controlled based on the control of the switching element having the overlapping section, and the switching loss during the commutation operation of the switching element is reduced by the resonance current of the resonance circuit. The generation of the resonance current of the resonance circuit is controlled by using the control of the switching element having the overlapping section, and the current and voltage of the switching element at the commutation source are made zero at the time of commutation by the resonance current generated by this control, Reduces switching loss during commutation operation.
[Selection] Figure 1

Description

  The present invention relates to a current source inverter device that supplies a current to a load such as a plasma load, and a control method for the current source inverter device.

  The current source inverter device includes a direct current reactor connected to a direct current source, a conversion unit that converts direct current power from the direct current reactor into alternating current power, and a control unit that drives and controls the switching element of the conversion unit. Since it can be handled as a current source, it has a feature that it acts in the direction of suppressing the fluctuation of the impedance of the load such as a load short circuit. For example, in the case of a plasma load, it acts in the direction of maintaining the plasma.

  Since the current source inverter device can stably supply current to the load even when the load fluctuates as described above, the current source inverter device can supply power to the plasma load whose impedance varies depending on the situation. Is suitable.

  For example, when the plasma is extinguished and the plasma load fluctuates in the open state, the voltage with respect to the plasma load of the current source inverter device increases. This voltage rise is a direction to promote plasma ignition, and facilitates ignition. Conversely, when an arc is generated on the plasma load side and the plasma load fluctuates in the short-circuit direction, the current source inverter device supplies a constant current to the load, so that the current is excessive to the plasma load. Since supply is suppressed, damage to the plasma load can be reduced.

  FIG. 15 is a diagram for explaining a configuration example of a current source inverter device. In FIG. 15, the current source inverter device 100 includes a current source step-down chopper circuit 101, a three-phase inverter circuit 102, and a three-phase transformer 103. The current source step-down chopper circuit 101 steps down the direct current input from an AC source and a rectifier circuit (not shown) by chopper-controlling the switching element Q1, and smoothes the current with a direct current reactor LF1 and inputs it to the three-phase inverter circuit 102. To do.

  A chopper circuit that performs orthogonal transformation may use a current source step-up / step-down chopper circuit instead of the current source step-down chopper circuit 101 described above.

The three-phase inverter circuit 102 performs commutation between the elements by controlling ignition and extinction of the switching elements Q _R , Q _S , Q _T , Q _X , Q _Y , and Q _{Z at} a predetermined timing. AC power is supplied to the phase transformer 103.

  In the current source inverter device, when all the switching elements cut off the energization current, an overvoltage is applied to the switching elements due to the current generated by the DC reactor, and there is a risk of element destruction. There is a problem that device breakdown occurs due to the generation of voltage.

  In order to prevent the destruction of the switching element due to such a load short circuit accident, the load current is detected to determine the energization period, the technology for controlling the switching element within this energization period, the current flowing through the switching element is detected, A technique for controlling a switching element based on a detected current is known (see Patent Document 1).

  In addition to the problem of surge voltage generation and switching loss due to current interruption, the current overlap time at which the current of the commutation source switching element becomes zero at the zero cross point of the load voltage is obtained, and the commutation destination switching element Is known to start commutation at a time earlier than the current overlap time obtained from the zero cross point of the load voltage (see Patent Document 2).

16 and 17 are diagrams for explaining switching loss at the time of commutation in the circuit operation of FIG. FIG. 16 shows a case where the commutation source and the commutation destination switching elements are commutated without overlapping. In this example, the switching element _{Q R} Tenryumoto, the commutation destination switching element _{Q S,} is set to ON state by a gate pulse signal _{G R} and _{G S,} respectively (FIG. 16 (a), (b) ). Since the rise of the falling gate pulse signal G _S of the gate pulse signal G _R is consistent, between the switching elements commutation is performed without overlapping. Here, the commutation source current _{I QR} and voltage _{V QR} flowing through the switching element _{Q R} (drain-source voltage of the switching element), as shown in FIG. 16 (c), (e), the wiring in the OFF state The time constant changes due to the influence of inductance, element capacity, load inductance, and the like. Therefore, ZCS and ZVS are not generated at the time of commutation, and a switching loss occurs. In addition, a surge voltage is generated, leading to damage to the switching element.

  Further, even in the case of providing an overlapping section where the ON state of the switching element at the commutation source and the commutation destination overlaps at the time of commutation, as shown in FIGS. Since it does not become ZCS and ZVS, a switching loss occurs.

  A resonant inverter is known as a soft switching inverter that reduces switching loss.

  In the resonant inverter, a commutation diode and a resonance capacitor are connected in parallel to a switching element, and a resonance circuit is configured by the resonance capacitor, a resonance inductance, and a switching element connected to the resonance circuit. ZVS (zero voltage switching) and ZCS (zero current switching) of the switching element are realized by charging / discharging of the resonance capacitor by the resonance current of the resonance circuit and conduction of the commutation diode (for example, Patent Document 2).

  In addition, since the resonance circuit has a configuration in which a resonance capacitor is connected in parallel to the switching element, there is a problem that the capacitance is increased by the capacitor. In order to solve this problem, a configuration in which a resonance circuit is formed by an auxiliary circuit including auxiliary switching elements has been proposed (Patent Document 3).

JP-A-8-298777 JP 2002-325464 A JP 2004-23881 A

  Conventionally proposed current source inverters need to detect, for example, load current and switching element current in order to control switching element driving timing to prevent switching loss and element destruction. Further, even in the configuration in which the switching element is controlled by detecting the current overlap time when the current of the commutation source switching element becomes zero, it is necessary to detect the load current and the load voltage in order to detect the current overlap time. .

  Therefore, in any configuration, it is necessary to provide a detector for detecting current and voltage, and a control circuit for generating a control signal for controlling the switching element based on the detected current and detection voltage is provided for a normal switching element. There is a problem that it is necessary to prepare other than the control circuit for controlling the operation.

  In the case of a resonant inverter, a resonant capacitor must be connected in parallel to the switching element, and a control circuit that forms a control signal for the switching element for the resonant circuit can be operated as a normal switching element. There is a problem that it is necessary to prepare other than the control circuit to be controlled.

  Therefore, in the known current source inverter device, in addition to controlling the switching operation normally performed for the commutation operation, it is necessary to control the switching element in order to prevent switching loss and element destruction. In addition to the control circuit that controls the operation of the switching element performed in a normal commutation operation, there is a problem that a control circuit that controls the switching element is necessary to prevent switching loss and element destruction.

  The present invention solves the above-described conventional problems and prevents switching loss of the switching element by a normal switching operation for commutation operation without requiring special control in the control of the switching element of the current source inverter. For the purpose.

  In the commutation operation of the current source inverter device, the present invention is sufficient for the fluctuation of the load current in the generation of the commutation overlap section in which both the commutation source switching element and the commutation destination switching element are turned on. In order to obtain a proper overlap time, a commutation overlap section in which the overlap time width (phase width) is set in advance is provided. Here, “fixed” means that the time width (phase width) of the commutation overlap section is set regardless of the load current fluctuation. The setting of the commutation overlap section controls the drive timing of the switching element. The resonance circuit is controlled by driving timing control in the commutation overlap section of the switching element, and the switching loss during the commutation operation of the switching element is reduced by the resonance current of the resonance circuit.

  According to the current source inverter device and the inverter control of the present invention, only the drive timing of the switching element at the time of commutation is changed, and the commutation overlapping section in which both the commutation source and the commutation destination switching elements are turned on is generated. In this case, even when the load current fluctuates, it is set in advance so that a sufficient overlap time width (phase) can be obtained, and the resonance current is supplied to the resonance circuit by controlling the switching element in the commutation overlap section. The switching loss is reduced by the resonance current.

  By using the resonance current in the commutation overlapping section, the switching element control for preventing the switching loss is performed in addition to the switching operation control normally performed for the commutation operation as in the conventional current source inverter device. Is unnecessary, and in addition to the control circuit for controlling the operation of the switching element performed in the normal commutation operation, the control circuit for preventing the switching loss is unnecessary.

  The present invention does not simply reduce the switching loss of the switching element by generating an overlapping section in which both the commutation source and the commutation destination switching elements are in the ON state, but controls the switching element having the overlapping section. To control the generation of resonance current of the resonance circuit, and the resonance current generated by this control makes the current and voltage of the switching element at the commutation zero during the commutation, thereby reducing the switching loss during the commutation operation. To do.

  The present invention includes an aspect of a current source inverter device and an aspect of a control method of the current source inverter device.

[Mode of current source inverter device]
The current source inverter device of the present invention includes a current source chopper unit that constitutes a DC source, a multi-phase inverter unit that converts the DC output of the current source chopper unit into multi-phase AC power by operation of a plurality of switching elements, A control unit that controls the chopper unit and the multiphase inverter unit, and a resonance circuit that supplies a resonance current to the switching element of the multiphase inverter unit are provided.

  The control unit controls the drive timing of the commutation destination and the commutation source switching element during commutation between the switching elements of the multiphase inverter unit. By controlling the drive timing of the switching element, an overlapping section in which both the commutation destination switching element and the commutation source switching element are turned on is generated, and the resonance current of the resonance circuit is controlled.

  In the overlapping section, the resonance current of the resonance circuit is supplied in the reverse bias direction to the switching element that is the commutation source, and is supplied in the forward bias direction to the commutation diode that is connected in reverse parallel to the switching element. By supplying this resonant current to the switching element and the commutation diode, the commutation source switching element is set to zero current and zero voltage in the overlap section, and the commutation source switching element is switched from the on state to the off state. Flow operation at zero current and zero voltage.

  The current source inverter device and the control method of the present invention are not limited to a three-phase inverter that converts DC power into three-phase AC power, but a multi-phase inverter that converts DC power into any multi-phase AC power of two or more phases Can be applied to.

  The resonance circuit of the present invention uses the output of the commutation destination switching element as the resonance current supply source, and in the overlapping section, the commutation destination switching element is turned on before the commutation source switching element is turned off. Thus, a forward current flowing through the switching element at the commutation destination is introduced into the resonant circuit to generate a resonant current.

  The resonance circuit of the present invention includes the same number of current supply terminals as the number of phases of AC power converted by the multiphase inverter unit. Each current supply terminal is connected to each connection terminal of the switching element which opposes in the bridge structure of the switching element which forms a multiphase inverter part.

  At the time of commutation between the switching elements of the multiphase inverter unit, a current is introduced into the resonance circuit from a current supply terminal connected to the switching element at the commutation destination to generate a resonance current. The resonance current generated by the resonance circuit is supplied to the commutation source switching element from a current supply terminal connected to the switching element at the commutation source. The current supplied from the resonance circuit to the commutation source switching element is introduced in the reverse bias direction of the switching element with respect to the commutation source switching element.

  Since the resonance current introduced into the commutation source switching element is in the opposite direction to the forward current flowing through the commutation source switching element, the forward current is canceled out and the current flowing through the commutation source switching element is zero current. And

Further, the resonance current flows through the commutation diode, thereby setting the voltage of the switching element at the commutation source to zero voltage. The zero current state and the zero voltage state of the commutation source switching element are continued in the overlapping section, and the commutation source switching element is switched from the on state to the off state in the zero current state and the zero voltage state. And commutation by ZCS is performed.

  The circuit configuration of the resonance circuit of the present invention can be configured to include an LC series circuit between the terminals formed by the current supply terminals, for example. The LC series circuit generates a resonance current by inputting the forward current of the switching element at the commutation destination during commutation between the switching elements of the multi-phase inverter unit, and generates the resonance current of the switching element of the commutation source. Supply in reverse bias direction.

When the multiphase inverter unit of the present invention converts DC power to n-phase AC power, the resonance circuit is configured so that the resonance current does not flow to the other switching elements that are turned on next. It is assumed that the reactance L and capacitance C of the LC series circuit satisfy the condition of (L × C) ^1/2 > π / n. When the multiphase inverter unit is a three-phase inverter circuit, the condition that the reactance L and the capacitance C of the LC series circuit should satisfy (L × C) ^1/2 > π / 3.

  When the reactance L and the capacitance C satisfy this condition, the phase corresponding to the half wavelength of the resonance current is attenuated before the next switching element is turned on, and the influence of the resonance current can be prevented.

  Further, when the multiphase inverter unit of the present invention converts DC power into n-phase AC power, the phase component θt in the overlapping section satisfies π / 2n> θt as a condition for preventing a short circuit between the switching elements. Shall.

  By satisfying the condition that the phase θt of the overlapping section satisfies π / 2n> θt, it is possible to prevent a short circuit between the two switching elements facing each other between the upper and lower sides of the DC power in the inverter bridge configuration. When the multiphase inverter is a three-phase inverter, the condition to be satisfied by the phase component θt of the overlapping section is π / 6> θt.

  In addition, as a condition for reducing the forward current flowing through the transfer source switching element to zero in the overlap section, it satisfies sin (θt)> (phase current of resonant circuit current / maximum peak value of resonance current). To do.

  By satisfying this condition, the forward current flowing through the commutation source switching element in the overlapping section can be made zero.

  From the condition of sin (θt)> (phase current of the multiphase inverter part / maximum peak value of the resonance current), the maximum peak value of the resonance current of the resonance circuit is larger than the phase current value of each phase of the multiphase inverter part. Set to be.

[Mode of control method of current source inverter device]
The control method of the current source inverter device of the present invention is a control method of the current source inverter device that converts the DC output of the current source chopper unit into multiphase AC power by the operation of a plurality of switching elements of the multiphase inverter unit. is there. At the time of commutation between the switching elements of the multiphase inverter unit, by controlling the drive timing of the commutation destination and the commutation source switching element, both the commutation destination switching element and the commutation source switching element are turned on. The generation of the overlapping section and the resonance current are controlled.

  In the overlapping section, the resonance current is supplied to the commutation source switching element in the reverse bias direction, and is supplied to the commutation diode connected in reverse parallel to the switching element in the forward bias direction. With this current supply, the commutation source switching element is set to zero current and zero voltage in the overlapping section, and the commutation operation at the time when the commutation source switching element switches from the on state to the off state is performed with zero current and zero voltage.

  The multiphase inverter unit includes a bridge configuration of switching elements and a resonance circuit connected between connection terminals of the switching elements facing each other in the bridge configuration. At the time of commutation between switching elements, a current to the switching element at the commutation destination is introduced into the resonance circuit to generate a resonance current, and the resonance current generated in the overlapping section is applied to the switching element at the commutation source. Supply in the reverse bias direction of the switching element.

  When the multiphase inverter unit is an inverter that converts DC power into n-phase AC power, the condition that the phase component θt of the overlapping section satisfies as a condition for preventing a short circuit between the switching elements is π / 2n> θt. is there. When the multiphase inverter section is a three-phase inverter circuit, the condition that the phase component θt of the overlapping section satisfies is π / 6> θt.

  In addition, the condition for reducing the forward current flowing through the transfer source switching element to zero in the overlapping section is sin (θt)> (phase current of the multiphase inverter unit / maximum peak value of the resonance current).

  By satisfying this condition, the forward current flowing through the commutation source switching element in the overlapping section can be made zero.

  From the condition of sin (θt)> (phase current of the multiphase inverter part / maximum peak value of the resonance current), the maximum peak value of the resonance current of the resonance circuit is larger than the phase current value of each phase of the multiphase inverter part. Set to be.

  As described above, according to the current source inverter device and the control method of the current source inverter device of the present invention, the control of the switching element of the current source inverter is usually performed for the commutation operation without requiring special control. Switching loss can prevent switching loss.

It is a figure for demonstrating the structural example of the current source inverter apparatus of this invention. It is a figure for demonstrating the other structural example of the current source inverter apparatus of this invention. It is a schematic block diagram and operation | movement figure of this invention current source inverter apparatus. It is a timing chart for demonstrating the commutation state of the switching element of the current source inverter apparatus of this invention. It is a figure for demonstrating the example of a structure of the inverter circuit and resonance circuit of this invention. It is a timing chart for demonstrating the drive of the switching element of this invention. It is a figure for demonstrating the resonance current of this invention. It is a figure for demonstrating the resonance circuit of this invention. It is a figure for demonstrating the condition of the overlap area and resonance circuit of this invention. It is a figure for demonstrating the commutation state of the switching element of this invention. It is a figure for demonstrating operation | movement of the inverter circuit and resonance circuit of this invention. It is a figure for demonstrating operation | movement of the inverter circuit and resonance circuit of this invention. It is a figure for demonstrating operation | movement of the inverter circuit and resonance circuit of this invention. It is a figure for demonstrating operation | movement of the inverter circuit and resonance circuit of this invention. It is a figure for demonstrating one structural example of a current source inverter apparatus. It is a figure for demonstrating the switching loss at the time of a commutation in an inverter. It is a figure for demonstrating the switching loss at the time of a commutation in an inverter.

BEST MODE FOR CARRYING OUT THE INVENTION

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following, the current source inverter device and the control method of the current source inverter device of the present invention will be described with reference to FIG. 1 and FIG. 2, and a configuration example of the current source inverter device will be described. An example of device control will be described. The inverter circuit and the resonance circuit of the present invention will be described with reference to FIGS. Here, a three-phase inverter is shown as an example of the multiphase inverter.

[Configuration example of current source inverter device]
First, a configuration example of the current source inverter device of the present invention will be described with reference to FIGS.

  The current source inverter device 1 of the present invention shown in FIG. 1 is input from a rectifying unit 10 that rectifies AC power of an AC power supply 2, a snubber unit 20 that forms a protection circuit that suppresses transiently generated high voltage, and a rectifying unit 10. A current source step-down chopper unit 30 that converts the voltage of the DC power into a predetermined voltage and outputs a DC current, a multi-phase inverter unit 40 that converts the DC output of the current source step-down chopper unit 30 into a multi-phase AC output, A multiphase transformer 50 that converts the AC output of the inverter 40 into a predetermined voltage, and a multiphase rectifier 60 that converts the AC of the multiphase transformer 50 into DC.

  A chopper unit that performs orthogonal transformation may use a current source step-up / step-down chopper unit instead of the current source step-down chopper unit 30 described above.

Current-step-down chopper 30, and a DC reactor _{L F1} and switching element _{Q 1,} a diode _{D 1.} The switching element Q ₁ is, steps down by chopper controlling the DC voltage rectified by the rectifier unit 10. The direct current reactor L _F1 smoothes the chopper-controlled direct current and inputs it to the multiphase inverter unit 40.

The control circuit 80, a chopper current of the current-step-down chopper unit 30, and inputs a detection value of the output voltage of the current source inverter device 1, the chopper control of the switching element Q ₁ so that a predetermined current and a predetermined output voltage To do.

The current source inverter device 1 of the present invention shown in FIG. 2 is an example in which the current source step-down chopper unit 30 is another configuration example. The current source step-down chopper unit 30 shown in FIG. 2 has a configuration in which an output capacitor _CF1 is connected in parallel to the output end.

In the configuration shown in FIG. 2, an output capacitor that is not provided in a normal current source step-down chopper is provided. By configuring the output capacitor C _F1 to be connected to the output terminal of the current source step-down chopper unit 30, a surge voltage generated when performing a commutation operation between the switching elements of the multiphase inverter unit 40, and each switching element The switching element can be protected by absorbing the energy of the inductance connected in series.

The value of the output capacitor C _F1 is set to such an extent that the current delay does not affect the commutation of the inverter operation due to the time constant due to the output capacitor and the wiring inductance.

  The polyphase inverter unit 40 includes a polyphase inverter circuit configured by bridge-connecting switching elements corresponding to the number of phases. For example, in the case of three phases, the three-phase inverter circuit is composed of six switching elements. As the switching element, for example, a semiconductor switching element such as an IGBT or a MOSFET can be used. Each switching element of the multiphase inverter circuit performs a switching operation based on the control signal of the switching control unit 81, converts DC power into AC power, and outputs the AC power.

  The multi-phase inverter unit 40 includes a resonance circuit 70, and introduces the resonance current generated by the resonance circuit 70 into a switching element in a commutation state of the multi-phase inverter circuit. The commutation of the switching element is performed with zero current and zero voltage. Do in state. The resonance circuit 70 of the present invention generates a resonance current in synchronization with the commutation operation of each switching element of the multiphase inverter circuit, introduces the resonance current into the commutation source switching element, and the commutation source switching element. Are commutated in a state of ZCS (zero current switching) and ZVS (zero voltage switching).

  The AC output of the polyphase inverter unit 40 can obtain a high frequency output by increasing the switching frequency of the switching element. When the plasma generator is used as the load unit, the current source inverter device supplies a high frequency output of, for example, 200 kHz to the load unit. In order to obtain a high-frequency output, the multi-phase inverter circuit performs a switching operation of the switching element at a high frequency. As described above, when the switching element is switched at a high frequency, the AC output includes a high frequency ripple component.

The polyphase rectification unit 60 is provided with a DC filter circuit in the output unit as an example of a configuration that removes the high-frequency ripple component included in the AC output of the polyphase inverter unit 40 in the same manner as an ordinary polyphase rectification circuit. DC filter circuit can be configured by the output reactor L _FO connected to the output capacitor C _FO in parallel connected in series to the output terminal.

The current source inverter device 1 outputs the direct current output of the multiphase rectification unit 60 via the wiring inductance L0 provided in the wiring without being required for the above-described direct current filter circuit, and generates plasma that becomes a plasma load with the current source inverter device 1 The output cable 3 can be connected to the device 4, and the parasitic impedance of the current source inverter device can be used as a configuration for removing the high frequency ripple component.

For example, the inductance of the wiring impedance 90 between the multiphase rectifier 60 and the output terminal, the capacitance of the inductance LFO included in the output cable connected between the current source inverter device 1 and the load, and the plasma load In this case, a filter circuit that removes a high frequency component similar to that of the DC filter circuit is configured by the electrode capacitance C0 of the plasma generator 4 to reduce the high frequency ripple component.

When the current source inverter device is used as a power supply source to the plasma generator, the load can be regarded as a short circuit when an arc is generated in the plasma generator 4 on the load side, and a DC filter circuit provided on the current source inverter device side. The arc energy Pc is supplied from the output capacitor CFO.

At this time, arc energy Pc outputted from the output capacitor C _FO can be expressed by the following equation (1).
_{Pc = 1/2 × C FO} × V O 2 + 1/2 × (L FO + L O) × I O 2 ... (1)

The arc energy Pc of the plasma generator 4 is preferably 1 mJ or less per 1 kW of output. This is because the inductances L _FO and L _O usually show a small value, and the energy (L _FO + L _O ) × I _O ² of the inductances L _FO and L _O can be ignored for 1 mJ / kW. Note that 1 mJ / kW represents energy in mJ per 1 kW output, and the energy for 100 kW output is 100 mJ. Therefore, when the arc energy Pc of the plasma generator 4 is less than 1mJ, the output capacitor C _FO value, by selecting a value or values of C _FO obtained as 1mJ the Pc of the formula (1), The arc energy Pc is not affected.

Accordingly, the current source inverter device, instead of the series filter circuits, the configuration using the parasitic impedance of the electrode capacitance of the wiring impedance and output cables and a plasma generator, capacitance component corresponding to the output capacitor C _FO is the arc energy Pc If it is large enough to be supplied, the high-frequency ripple component can be removed and the arc energy Pc can be supplied.

Further, the high-frequency ripple component has a characteristic that increases when the driving frequency of the multiphase inverter circuit is lowered. Therefore, by increasing the driving frequency of the polyphase inverter circuit, the need for output capacitors C _FO and output reactor L _FO can be reduced. Further, by increasing the drive frequency of the multiphase inverter circuit, it is possible to suppress the energy held in the current source inverter device 1 inside.

[Example of commutation operation of current source inverter device]
Next, an example of commutation operation in the current source inverter device of the present invention will be described based on an example of a three-phase inverter with reference to FIGS.

  FIG. 3 is a schematic configuration diagram and an operation diagram of the current source inverter device, and FIG. 4 is a timing chart for explaining a commutation state of the switching element of the current source inverter device. In FIG. 3, the state of current flowing through the element and the wiring is shown by shading, the conduction state is shown by dark display, and the non-conduction state is shown by light display.

Current source inverter system shown in FIG. 3, six switching elements _{Q R, Q S, Q T} , Q X, Q Y, will be a _{Q Z} bridge connection, a switching element _{Q R} and the switching element _{Q x} The switching element Q _S and the switching element Q _Y are connected in series, and the switching element Q _T and the switching element Q _z are connected in series.

A connection point between the switching element Q _R and the switching element Q _x is connected as an R phase component of the three-phase transformer 51 via an inductance L _m1 , and a connection point between the switching element Q _S and the switching element Q _Y is an inductance L _m2. It is connected as S-phase of the three-phase transformer 51 via a connection point of the switching element Q _T and the switching element Q _Z are connected as T-phase of the three-phase transformer 51 via an inductance L _m3.

The connection, the connection point of the switching element Q _R and the switching element Q _x, the connection point of the switching elements Q _S and the switching element Q _Y, and the terminals of each resonant circuit connection point of the switching element Q _T and the switching element Q _Z Then, a resonance current is supplied from the resonance circuit.

The timing chart of FIG. 4 shows a rolling flow Sample images between the switching element Q _R and the switching element Q _S. Here, the switching element Q _R is the commutation source of the switching element, and a switching element Q _S and commutation destination switching element.

  In the current source inverter device of the present invention, the commutation operation is controlled so that an overlapping section is generated in which both the commutation source switching element and the commutation destination switching element are turned on, and the commutation operation is synchronized with the commutation operation. Thus, the resonance current of the resonance circuit is controlled and supplied to the switching element of the commutation source.

Generation of overlapping sections and a switching element Q _S of the commutation source of the switching element Q _R and commutation destination are both turned on, the gate pulse signal G _S of the switching element Q _{S (FIG.} 4 (b)) rises Timing the by before and falls gate pulse signal _{G R} of the switching element _{Q R} (FIG. 4 (a)), a gate pulse signal _{G R} for the switching element _{Q R} turned on (FIG. 4 (a)) This is performed by temporally overlapping the gate pulse signal G _S (FIG. 4B) that turns on the switching element Q _S. Therefore, the switching element Q _S turned on before the switching element Q _R is switched from the ON state to the OFF state, within the overlap interval, the switching element Q _R and the switching element Q _S are both turned on.

Hereinafter, the sections A, B, C, and D in FIG. 4 will be described.
(Section A):
A section in FIG. 4 is a switching element _{Q R} is turned on, the current _{I QR} (FIG. 4 (c)) flows to the switching element _{Q R,} a current _{I QS} of the switching element _{Q S} (FIG. 4 (d)) Does not flow.

FIG. 3A shows an operating state and a current state of the switching element in the A section. Current _{I QR} of the switching element _{Q R} (FIG. 4 (c)) is supplied to the three-phase transformer 51 as R-phase primary current _{I R} (FIG. 4 (h)), the flow returns through the switching element _{Q Z.}

(B section):
The switching element Q _S is turned on by the gate pulse signal G _S , and the current I _QS (FIG. 4D) starts to flow through the switching element Q _S. At this time, current _{I QS} of the switching element _{Q S,} the resonance circuit 70, the inductance _{L m1,} to increase a time constant which is obtained based on inductance _{L m @ 2,} on the time of the switching element _{Q S} is ZCS (zero current switching) is performed ( FIG. 4 (d)).

In synchronization with the rise time of the switching element Q _S, it starts the resonant current flows through the resonant circuit 70 (FIG. 4 (g)). Resonance current flows in the reverse bias direction to the switching element Q _R. The resonance current, since in the switching element _{Q R} is a forward current _{I QR} opposite direction, decreases by canceling the current _{I QR} (FIG. 4 (c)). The circled symbols 1 in FIGS. 4 (c) and 4 (g) indicate currents in a canceling relationship.

FIG. 3B shows an operating state and a current state of the switching element in the B section. A forward current of the switching element Q _R is offset by the resonance current, 3 phase transformers 51, the primary current due to the part of the resonant current I _{R (FIG.} 4 (h)) and the primary current I by the switching element Q _{S S} (FIG. 4 (h)) is supplied, returns through the switching element _{Q Z.}

(C section):
At the end of the B interval, current _QR of the switching element Q _{R (FIG.} 4 (c)) becomes resonant current (FIG. 4 (g)) zero current is offset by the excess of the resonance current, the switching element Q _R starts to flow as a parallel-connected commutation diode _{D R} in diode current _{I DR} (FIG. 4 (e)) to. The circled symbols 2 in FIGS. 4E and 4G indicate currents in a corresponding relationship.

The beginning of section C interval following the B section, the switching element Q _R and the switching element Q _S is in both turned on. In this interval, current _{I QR} of the switching element _{Q R} (FIG. 4 (c)) is a resonant current continues to be offset by (FIG. 4 (g)) to maintain a zero current, the current _QS switching element _{Q S} (FIG. 4 (D)) increases as the resonance current increases. Thus, the voltage _{V D-S} between the drain and source of the switching element _{Q R} is held at zero voltage (FIG. 4 (f)).

In Section C, the gate pulse signal G _R falling by commutation source of the switching element Q _R of is off, although the switching element Q _R is off, the switching element Q _S is turned on, each other Different on / off states. In this state, the switching element Q _R is eliminated is offset by the resonance current stops flowing current I _QR in the OFF state, the resonant current flows through the commutation diode D _R subsequently.

Therefore, current I _QR flowing through the switching element Q _R, following the zero-current state by resonance current, the switching element Q _R commutation source is held zero-current state by the OFF state, the commutation source switching element _{Q R} is ZCS (zero current switching) is achieved.

Further, the resonant current by flowing through the commutation diode D _R of the switching element Q _R, the switching element Q _R of the commutation source ZVS (zero voltage switching) is achieved. This section C ends when the resonance current becomes zero.

FIG. 3C shows an operating state and a current state of the switching element in the C section. Resonance current, offset the forward current of the switching element Q _R is set to zero current and zero voltage by flowing through the commutation diode D _R. The three-phase transformer 51, the primary current _{I S} by the primary current _{I R} and the switching element _{Q S} by part of the resonant current is supplied, returns through the switching element _{Q Z} (FIG. 4 (h)).

(D section):
When the resonant current becomes zero, the voltage V _QR between the drain and source of the switching element Q _R DC voltage component is applied (FIG. 4 (f)).

In the operation state shown in FIGS. 3 and 4, the primary current I _S of the primary current I _R and S phases of the R phase flows as the primary current between the three-phase transformer 51 side. Current _{I QR} flow as the section A, the primary current _{I R,} Section B, the after commutated to the primary current _{I S} from the primary current _{I R} in C, and a current flows _{I QS} as the primary current _{I S} in the interval D.

In the primary current I _R and the primary current I _S flows both intervals during commutation, the primary current I _R and the primary current I _S to have the same current value, flows through half of the current when one of the primary current flows. Primary current I _R and the primary current I _S both flow section is a portion except a section switch to section D among the FIG 4 (h) In the section C is carried out.

In the section B in FIG. 4 in (h), the primary current I _R decreases towards the middle of the current, the primary current I _S increases towards the middle of the current. Further, in the section C in FIG. 4 (h), the at switching part to section D, the primary current I _R decreases towards the middle of the current to zero current, the primary current I _S from the middle of the current in the primary current It increases toward the total current.
By the switching operation from the current I _QR to the current I _QS , the primary current is supplied from the current source step-down chopper unit to the three-phase transformer 51 without being cut off.

FIG. 3D shows the operating state and current state of the switching element in the D section. The resonance current stops, and the three-phase transformer 51 is supplied with the primary current I _S by the switching element Q _{S and} returns through the switching element Q _Z.

  By the above commutation operation, the resonance current of the resonance circuit is supplied in the reverse bias direction to the switching element of the commutation source in the overlapping section, and the forward bias direction is applied to the commutation diode connected in reverse parallel to the switching element. The commutation source switching element is set to zero current and zero voltage in the overlapping section, and the commutation operation at the time when the commutation source switching element switches from the on state to the off state is performed with zero current and zero voltage. Do.

  Next, aspects of the current source inverter device and the control method of the current source inverter device of the present invention will be described.

  A mode of a current source inverter device and a control method of the current source inverter device of the present invention will be described with reference to FIGS. FIG. 5 shows a configuration example of the inverter circuit and the resonance circuit of the present invention, FIG. 6 shows a timing chart for explaining the driving of the inverter circuit switching element of the present invention, and FIG. 7 explains the resonance current of the resonance circuit of the present invention. FIG. 8 shows a diagram for explaining the resonance circuit of the present invention, FIG. 9 shows a diagram for explaining the inverter control overlap section and the condition of the resonance circuit of the present invention, and FIG. 10 is a diagram for explaining the commutation state of the switching element of the inverter circuit of the present invention, and FIGS. 11 to 14 are diagrams for explaining the operation of the inverter control of the present invention. In FIGS. 11 to 14, the current state flowing through the element and the wiring is shown in shades, the conduction state is shown in dark display, and the non-conduction state is shown in pale display.

  The resonant circuit of the present invention includes an LC series circuit between each terminal formed by the current supply end of the resonant circuit. Each LC series circuit generates a resonance current by inputting a forward current from the switching element at the commutation destination during commutation between the switching elements of the inverter circuit, and the generated resonance current is reversed from the switching element at the commutation source. Supply in the bias direction.

The inverter circuit 41 shown in FIG. 5 (a), six switching elements _{Q R, Q S, Q T} , Q X, Q Y, will be a _{Q Z} bridge-connected switching elements _{Q R} and the switching element _{Q x} Are connected in series, the switching element Q _S and the switching element Q _Y are connected in series, and the switching element Q _T and the switching element Q _z are connected in series.

A connection point _R between the switching element Q _R and the switching element Q _x is connected as an R phase component of the three-phase transformer 51 via an inductance L _m1, and a connection point S between the switching element Q _S and the switching element Q _Y is an inductance through L _{m @ 2} are connected as S-phase of the three-phase transformer 51, a switching element Q _T and the switching element Q _Z connecting point T is connected as T-phase of the three-phase transformer 51 via an inductance L _m3 The

Resonant circuit 71 is provided with three sets of resonance circuit consisting of the series connection of a capacitor C _L and a reactance L _C, each end of the three sets of resonator circuit is connected between the three current supply end terminal. Each terminal of the current supply end has a connection point _R between the switching element Q _R and the switching element Q _X, a connection point _S between the switching element Q _S and the switching element Q _Y , and a connection point _T between the switching element Q _T and the switching element Q _Z. Connected to.

With this configuration, at the time of commutation of the switching element Q _R and the switching element Q _S current I _cs is supplied to the resonant circuit 71 from the connecting point S, a connection point at the time of commutation of the switching element Q _S and the switching element Q _T T current I _cT is supplied to the resonant circuit 71 from the time the commutation of the switching element Q _T and the switching element Q _R current I _cR is supplied to the resonant circuit 71 from the connecting point R.

The resonance circuit 71 generates a resonance current by inputting a forward current of a switching element that is a commutation destination of two switching elements that perform a commutation operation. Further, the resonance circuit 71 supplies the generated resonance current in the reverse vice direction of the commutation source switching element of the two switching elements performing the commutation operation. For example, when performing commutation between the switching element Q _R and the switching element Q _S, the resonance circuit 71 generates a resonant current to enter the forward current of the switching element Q _S is commutation destination supplies current the generated resonance current in the reverse bias direction of the switching element Q _R is the commutation source. In addition, although the resonance circuit 71 has shown the structure of (DELTA) form connection in Fig.5 (a), it is good also as a structure by the star connection shown in FIG.5 (b).

The timing chart for explaining the driving of the switching elements of the inverter circuit of the present invention in FIG. 6 shows gate pulse signals for driving the switching elements Q _R , Q _S , Q _T , Q _X , Q _Y , Q _Z. Because here shows an example of a three-phase inverter, when one cycle of driving angular frequency omega _I of the three-phase inverter and the phase fraction of 2 [pi, the section which is turned in each phase of the switching element (2 [pi / 3 ) Phase. In FIG. 6, one cycle is divided into a total of 12 sections with a phase of π / 6 as one section. Incidentally, when the driving frequency of the 3-phase inverter was _{f I,} driving angular frequency omega _I is ω _I = 2π × _{f I.}

  In the present invention, a resonance current is generated in the resonance circuit by providing an overlapping section θt between two switching elements in a commutation relationship, and the generated resonance current is supplied to the commutation source switching element. The commutation source switching element is commutated by ZCS (zero current switching) and ZVS (zero voltage switching), thereby reducing the switching loss during commutation.

(Overlapping section θt, setting of resonance circuit)
Hereinafter, the overlapping section θt necessary for the commutation operation of ZCS (zero current switching) and ZVS (zero voltage switching) will be described.

Figure 7 shows the relationship between the overlap period θt and the resonance current _{I CL} for R-phase primary current _{I R,} 7 (a) shows a resonance current _{I CL} and R-phase primary current _{I R,} 7 ( b) shows a gate pulse signal G _R for driving and controlling the switching element Q _R, FIG. 7 (c) shows a gate pulse signal G _S for driving and controlling the switching element Q _S. FIG. 8 shows a configuration example of the resonance circuit.

In the overlapping section θt at the time of commutation, the resonance current I _CL generated by the resonance circuit formed by connecting the capacitor C _L and the reactor L _C of the resonance circuit in series is converted into the equivalent capacitance C _e and the equivalent reactor L _e of the resonance circuit. Is expressed by the following formula (2).
I _CL = I _max × sin _{ω n} t (2)
Here, the maximum value I _max of the resonance current and the angular frequency ω _n of the resonance circuit are expressed by the following equations (3) and (4), respectively.
I _max = V _RS / (L _e / C _e ) ^1/2 (3)
ω _n = 1 / (L _e × C _e ) ^1/2 (4)

V _RS , L _e and C _e are a voltage, an equivalent reactor, and an equivalent capacitance between the R terminal and the S terminal of the resonance circuit shown in FIG. 8 (b) is an equivalent circuit of the resonant circuit when commutated into S phase from R-phase, L _e and C _e for I _CT current does not flow at this time T phase viewed from between R-S phases It can be handled as a synthetic impedance circuit.

The equivalent reactor L _e and the equivalent capacitance C _e are expressed by the following equations (5) and (6).
L _e = 2/3 × L _C (5)
C _e = _3/2 × C _L (6)
Angular frequency omega _n of the resonant circuit, Sadamari a capacitor C _L and the reactor L _C resonant circuit as shown in equation (4) to (6), is a unique angular frequency to the resonant circuit.

In FIG. 7A, the time t _P when the resonance current I _CL reaches the maximum peak value I _max is expressed by the following formula (7) from the relationship of ω _n × t _P = π / 2.
t _P = π / 2 × 1 / ω _n = π / 2 × (L _C × C _L ) ^1/2 (7)

When the commutation source switching element Q is commutated, the current between the commutation diode D of the switching element Q is made conductive, thereby setting the drain-source voltage of the switching element to zero voltage and ZVS (zero voltage switching). Can do. The supply current to the commutating diode D supplies a primary current I _R min to a three-phase transformer, the maximum peak value I _max of the resonant current I _CL represented by the formula (3), in each phase _{, I max> I R, I} max> I S, to be in the range of _I max> _{I T,} selecting the capacitor _{C L} and a reactor _{L C} at the resonant circuit.

  In FIG. 7, the maximum range of the overlapping section θt is π corresponding to a half cycle of the resonance current. When the overlap section θt is set to exceed the half period π of the resonance current, the resonance current is already attenuated to zero when the overlap section θt ends and the commutation source switching element is turned off. For this reason, the commutation diode of the switching element that is the commutation source cannot be brought into conduction to obtain a zero voltage state.

  Therefore, in order to achieve ZVS (zero voltage switching), the overlapping section θt is set within π for a half period of the resonance current.

Figure 9 is a diagram for explaining the conditions for setting the capacitor C _L and the reactor L _C of overlapping sections θt and the resonant circuit. Figure 9 (a), (b) shows the timing of gate pulse signal of the switching element Q _R and Q _X in the connection relationship in the bridge configuration, FIG. 9 (c), the a connection relationship in (d) of the bridge structure The timings of the gate pulse signals of the switching elements Q _S and Q _Y are shown. FIGS. 9G and 9H show the timings of the gate pulse signals of the switching elements Q _T and Q _Z which are connected in the bridge configuration. ing. Further, FIG. 9 (e) shows a resonance current _{I CL} of the resonant circuit connected between the switching element _{Q R} and the switching element _{Q S,} FIG. 9 (f) is the forward current _{I QR} flowing through the switching element _{Q R} Show.

In the current source inverter device of the present invention, the conditions for performing the commutation operation and the switching operation of ZCS and ZVS are as described above.
(A) The maximum peak value I _max of the resonance current I _CL is in a range of I _max > I _R , I _max > I _S , and I _max > I _T in each phase.
(B) The maximum range of the overlapping section θt is π corresponding to a half period of the resonance current.
There are conditions.

  The following conditions (c), (d), and (e) are required for the overlapping section and the resonance circuit. These conditions (c), (d), and (e) are indicated by symbols A, B, and C in FIG. 9, respectively.

  (C) The condition for preventing a short circuit between switching elements in a connection relationship in the bridge configuration is π / 3> θt.

When the overlap period θt is increased, for example, as indicated by symbol A in FIG. 9, between the switching elements such as a switching element Q _R and the switching element Q _X in the connection relationship will short-circuit in the bridge configuration. In order to prevent this short circuit between the switching elements, a condition of π / 3> θt (ω _I × T _n ) is required. Note that _{T n} is the time width, omega _I is a three-phase inverter driving angular frequency of the resonance current _{I CL.}

  In addition, when the overlap period is formed by extending the period in which each switching element is in the ON state by an arbitrary time width equal to the front and rear in the time direction, each extension period is shorter than π / 6. It becomes.

(D) The condition for the resonance current I _CL not to depend on the next generation mode of the resonance current is (L _c × C _L ) ^1/2 <1 / (3ω _I ). ωI is the driving angular frequency of the three-phase inverter circuit.

As indicated by reference numeral B in FIG. 9, after the switching element Q _S is turned on, the switching element Q _X is turned on after π / 3 and the next resonance current starts to flow. _The resonance current I _CL generated when _S is turned on needs to end within π / 3.

When the time width of the resonance current I _CL is T _n and the driving angular frequency ω _I of the three-phase inverter, the condition that the resonance current I _CL is within π / 3 is expressed by ω _I × T _n <π / 3. .

On the other hand, in the resonance circuit, the time width T _n of the resonance current I _CL corresponds to a half period π, and therefore, there is a relationship of T _n = π / ω _n . Note that ω _n is an angular frequency of the resonance circuit.

Therefore, from the above relationship, “ω _I × T _n <π / 3”, which is a condition that the resonance current I _CL is within π / 3, is expressed by the condition required for the capacitor C _L and the reactor L _C of the resonance circuit. And (L _c × C _L ) ^1/2 <1 / (3ω _I ).

(E) The condition for the current I _QR to decrease to zero during the overlap interval θt is sin (θt)> I _QR / I _{max as} indicated by the symbol C in FIG.

To achieve ZCS (zero current switching) must current I _QR of the switching element Q _R of the commutation source within a period of overlap interval θt becomes zero, the resonant current I to decrease the current I _{QR CL} needs to be larger than the current I _QR at least at the last time of the overlapping section θt, and it is necessary to satisfy the condition of I _CL > I _QR . From the relationship of I _CL = I _max sin (θt), this condition is expressed by sin (θt)> I _QR / I _max .

Next, an example of commutation operation by the current source inverter device of the present invention will be described using the timing chart of FIG. Here, in the operation mode shown in FIG. 6 shows the commutation operation between the switching elements Q _R and the switching element Q _S of the operation mode 4, 5 and 6.

The switching element Q _R is the commutation source of the switching element, and a switching element Q _S and commutation destination switching element. Current source inverter device controls the commutation operation so that the commutation source of the switching element Q _R and commutation destination overlap interval switching element Q _S are both turned on is generated, commutation destination switching by introducing the forward current that flows when the element Q _S is turned on to the resonant circuit 71, in synchronization with the commutation operation to generate a resonance current in the resonance circuit, the generated resonant current commutation source It is supplied to the switching element _{Q R.}

Commutation source of the switching element Q _R and commutation destination overlapping section and the switching element Q _S are both turned on, the timing gate pulse signal G _{S (FIG.} 10 (b)) rises of the switching element Q _S, the switching element _{Q R} of the gate pulse signal _{G R} (FIG. 10 (a)) are those in which the up fall timing, the gate pulse signal _{G R} (FIG. 10 (a)) to the switching element _{Q R} oN state and An overlapping section is formed by temporally overlapping the gate pulse signal G _S (FIG. 10B) that turns on the switching element Q _S.

Therefore, the switching element Q _S is turned on before the switching element Q _R is switched from the ON state to the OFF state, the inside overlap period [theta] t (operation mode 5), the switching element Q _R and the switching element Q _S is a both turned on Become.

  Hereinafter, as in FIG. 4, the sections A, B, C, and D in FIG. 10 will be described. The A section corresponds to the operation mode 4, the B section corresponds to a part of the operation mode 5, the C section corresponds to the remaining part of the operation mode 5, and the D section corresponds to the operation mode 6.

(Section A):
A section in FIG. 10 is a switching element _{Q R} is in the ON state, the current _{I QR} flows to the switching element _{Q R,} a current _{I QS} of the switching element _{Q S} (FIG. 10 (c)) does not flow.

FIG. 11 shows the operating state and current state of the switching element in section A. Current _{I QR} of the switching element _{Q R} is supplied to the three-phase transformer 51 as R-phase primary current _{I R,} back through the switching element _{Q Z.}

(B section):
The switching element Q _S is turned on by the gate pulse signal G _S , and the current I _QS starts to flow through the switching element Q _S. At this time, since the current _{I QS} of the switching element _{Q S} which increases with a time constant due to inductance _{L m @ 2} and _{L C,} turn-on time of the switching element _{Q S} is performed (ZCS) zero-current switching) (FIG. 10 (d) ).

A resonance current I _CL is generated in the resonance circuit 71 by introducing the forward current I _QS flowing through the switching element Q _S in the ON state into the resonance circuit 71 (FIG. 10G). The resulting resonant current I _CL is introduced into the reverse bias direction with respect to the commutation source of the switching element Q _R. Introduced resonant current _{I CL,} since the switching element _{Q R} is a forward current _{I QR} opposite direction, it decreases by canceling the current _{I QR} (FIG. 10 (c)). A circled symbol 1 in FIGS. 10C and 10G indicates a current component in a canceling relationship.

FIG. 12 shows the operating state and current state of the switching element in section B. Current of the switching element Q _S is introduced into the resonant circuit 71 through the terminal S, the resonance current I _CL is generated by the resonance circuit comprising a series connection of a capacitor C _L and the reactor L _C. Part of the resonant current I _CL is supplied to the three-phase transformer 51 as a primary current of the R-phase, and the remaining portion is supplied to the reverse bias direction to the switching element Q _R of the commutation source.

A forward current of the switching element Q _R is offset by the resonance current, to a three-phase transformer 51, the primary current I _S by the primary current I _R and the switching element Q _S by part of the resonant current is supplied, the switching element Return through Q _Z.

(C section):
Current _{I QR} of the switching element _{Q R} is zero current. Surplus of the resonant current flows to the parallel-connected to the switching element Q _R commutating diode D _R. A circled symbol 2 in FIGS. 10E and 10G indicates a current component in a corresponding relationship.

Thus, the drain-source voltage of the switching element Q _R is held at zero voltage (FIG. 10 (f)). Within this Section C, the overlap interval ends when the gate pulse signal G _R falls commutation source of the switching element Q _R.

During commutation source off of the switching element Q _R, a current I _QR flowing through the switching element Q _R, following the zero-current state by resonance current by the switching element Q _R of the commutation source is turned off zero The current state is maintained. Therefore, the switching elements Q _R of the commutation source ZCS (zero current switching) is achieved.

Further, the resonant current by flowing through the commutation diode D _R of the switching element Q _R, the switching element Q _R of the commutation source ZVS (zero voltage switching) is achieved. This section C ends when the resonance current becomes zero.

FIG. 13 shows the operating state and current state of the switching element in section C. Resonant current I _CL is offset forward current of the switching element Q _R is set to zero current and zero voltage by flowing through the commutation diode D _R. The three-phase transformer 51, the primary current I _S by the primary current I _R and the switching element Q _S by part of the resonant current is supplied, it returns through the switching element Q _Z.

(D section):
When the resonant current becomes zero, the drain-source voltage V _QR of the switching element Q _R DC voltage component is applied (FIG. 10 (f)).

Incidentally, the primary current I _R of the R-phase, commutation occurs in the interval B, I _R and I _S becomes the same current in the section C, further commutation occurs at the end of the section from C, current I _QR It switches to the current I _QS (FIG. 10 (h)) and is supplied to the three-phase transformer 51 without being cut off.

FIG. 14 shows the operating state and current state of the switching element in section D. Resonant current _{I CL} stops, the primary current _{I S} by the switching element _{Q S} is supplied to the 3-phase transformer 51, back through the switching element _{Q Z.}

  By the above commutation operation, the resonance current of the resonance circuit is supplied in the reverse bias direction to the switching element that is the commutation source in the overlapping section, and the forward bias direction is applied to the commutation diode that is connected in reverse parallel to the switching element. The commutation source switching element is set to zero current and zero voltage in the overlapping section, and the commutation operation at the time when the commutation source switching element switches from the on state to the off state is performed with zero current and zero voltage. Do.

  In the commutation operation of the inverter according to the present invention, the drive timing of the commutation destination and the commutation source switching element can be performed in a plurality of forms in the formation of the overlapping section in which the switching elements are both turned on. For example, a form in which the timing for switching the commutation destination switching element from the off state to the on state is advanced, a form in which the timing for switching the commutation source switching element from the on state to the off state is delayed, and the commutation destination switching element in the off state The timing for switching from the ON state to the OFF state and the timing for switching the commutation source switching element from the ON state to the OFF state can be delayed.

  Note that the descriptions in the above-described embodiments and modifications are examples of the current source inverter device and the control method of the current source inverter device according to the present invention, and the present invention is not limited to each embodiment. Various modifications can be made based on the spirit of the invention, and these are not excluded from the scope of the present invention.

  The current source inverter device of the present invention can be applied as a power source for supplying power to the plasma generator.

DESCRIPTION OF SYMBOLS 1 Current source inverter apparatus 2 AC power supply 3 Output cable 4 Plasma generator 10 Rectification part 20 Snubber part 30 Current source step-down chopper part 40 Multiphase inverter part 41 Inverter circuit 42 Inverter circuit 50 Multiphase transformer part 51 Three-phase transformer 60 Many Phase rectifier 70 Resonant circuit 71 Resonant circuit 72 Resonant circuit 80 Control circuit unit 81 Switching controller 90 Wiring impedance 100 Current source inverter device 101 Current source step-down chopper circuit 102 Three phase inverter circuit 103 Three phase transformer

Claims (10)

A current source chopper unit constituting a DC source, a multi-phase inverter unit for converting a DC output of the current source chopper unit into multi-phase AC power by operation of a plurality of switching elements, the current source chopper unit and the multi-phase A control unit that controls the inverter unit, and a resonance circuit that supplies a resonance current to the switching element of the multiphase inverter unit,
The controller is
At the time of commutation between the switching elements of the multiphase inverter unit,
By controlling the drive timing of the commutation source switching element and the commutation destination switching element that perform commutation between phases ,
A switching element of one phase of the commutation source and a switching element of the other phase of the commutation destination both generate an overlapping section , and
In the commutation source and commutation destination switching elements that perform commutation between phases, a switching element of one phase of the commutation source, a switching element of the other phase of the commutation destination, and a closed circuit of the resonance circuit are formed,
The resonance current of the resonance circuit is supplied in a reverse bias direction to the commutation source switching element in the overlapping section, and to the commutation diode connected in reverse parallel to the commutation source switching element. By supplying in the forward bias direction, the switching element of the commutation source is set to zero current and zero voltage in the overlapping section,
A current source inverter device characterized in that a commutation operation at a time when a switching element of a commutation source is switched from an on state to an off state is performed with zero current and zero voltage. The resonance circuit includes the same number of current supply terminals as the number of phases of AC power converted by the multiphase inverter unit,
Each of the current supply terminals is connected to each connection terminal of the switching elements facing each other in the bridge configuration of the switching elements forming the multiphase inverter unit,
The resonant circuit is at the time of commutation between switching elements of the multi-phase inverter unit.
A current is introduced into the resonance circuit from the current supply terminal connected to the switching element at the commutation destination to generate a resonance current, and the resonance current is transferred from the current supply terminal connected to the switching element at the commutation source to the closed circuit. 2. The current source inverter device according to claim 1, wherein a resonance current is supplied in a reverse bias direction of the switching element to the commutation source switching element by flowing the current. The resonant circuit includes an LC series circuit between each terminal formed by the current supply end,
At the time of commutation between the switching elements of the multiphase inverter unit,
The LC series circuit receives a forward current of a switching element as a commutation destination, generates a resonance current, and supplies the resonance current in a reverse bias direction of the switching element as a commutation source. 2. The current source inverter device according to 2. The multi-phase inverter unit is an inverter that converts DC power into n-phase AC power;
The resonance circuit has a condition that the resonance current does not flow to another switching element that is turned on next.
The reactance L and capacitance C of the LC series circuit constituting the resonance circuit are (L × C) ^1/2 <1 / (n × ω _I ) with respect to the driving angular frequency ω _I of the n-phase multiphase inverter unit. The current source inverter device according to claim 3, wherein: The multi-phase inverter unit is an inverter that converts DC power into n-phase AC power;
The phase section θt of the overlapping section is
As a condition for preventing a short circuit between the switching elements, π / 2n> θt is satisfied,
It is characterized by satisfying sin (θt)> (phase current / maximum peak value of resonance current of the multiphase inverter section) as a condition for reducing the forward current flowing through the transfer source switching element to zero in the overlapping section. The current source inverter device according to any one of claims 1 to 4.   5. The current source inverter according to claim 1, wherein a maximum peak value of a resonance current of the resonance circuit is larger than a phase current value of each phase of the multiphase inverter unit. 6. apparatus. In a control method of a current source inverter device that converts a direct current output of a current source chopper unit into multiphase AC power by operation of a plurality of switching elements of the multiphase inverter unit, commutation between the switching elements of the multiphase inverter unit At times
By controlling the drive timing of the commutation source and commutation destination switching elements that perform commutation between phases, the switching element of one phase of the commutation source and the switching element of the other phase of the commutation destination are both turned on. And generate an overlapping interval
In the commutation source and commutation destination switching elements that perform commutation between phases, a switching element of one phase of the commutation source, a switching element of the other phase of the commutation destination, and a closed circuit of the resonance circuit are formed,
In the overlapping section, the resonance current is supplied in the reverse bias direction to the commutation source switching element, and is supplied in the forward bias direction to the commutation diode connected in reverse parallel to the commutation source switching element. By setting the commutation source switching element to zero current and zero voltage in the overlapping section,
A control method for a current source inverter device, characterized in that a commutation operation at a time when a commutation source switching element switches from an on state to an off state is performed with zero current and zero voltage. The multi-phase inverter unit includes a bridge configuration of a switching element and a resonance circuit connected between connection terminals of the switching elements facing each other in the bridge configuration.
At the time of commutation between the switching elements, a current to the switching element at the commutation destination is introduced into the resonance circuit to generate a resonance current,
8. The method of controlling a current source inverter device according to claim 7, wherein the generated resonance current is supplied in a reverse bias direction of the switching element to the commutation source switching element in the overlapping section. The multi-phase inverter unit is an inverter that converts DC power into n-phase AC power;
The phase section θt of the overlapping section is
As a condition for preventing a short circuit between the switching elements, π / 2n> θt is satisfied,
It is characterized by satisfying sin (θt)> (phase current / maximum peak value of resonance current of the multiphase inverter section) as a condition for reducing the forward current flowing through the transfer source switching element to zero in the overlapping section. The control method of the current source inverter device according to claim 7 or 8.   10. The current source inverter according to claim 7, wherein a maximum peak value of a resonance current of the resonance circuit is larger than a phase current value of each phase of the multiphase inverter unit. 10. Control method of the device.